How can meat think? What kind of thing, or process, might thinking and problem-solving be, such that physical stuff, nicely organised, can make it happen? More generally, how does order spontaneously arise in a physical universe? And what kinds of conceptual bridge link mathematics, physics and the biology and chemistry of life and mind? The interests of Alan Turing were remarkably various. In the 21 essays gathered here by Christof Teuscher, there is the mathematical biologist in search of new explanations of the emergence of patterns in nature; the proto-connectionist investigating neurally-inspired models of learning and cognition; the code-breaker, whose wartime contributions were crucial to the Allies' success; and the fledgling roboticist, whose ideas concerning machines' use of active learning to develop human-like intelligence are increasingly influential. There is also the putative father of so-called hypercomputation, or computation that soars beyond the (well-defined) limits of Turing's own formal account of computability. There is some hot controversy in the book over the technical possibility of hypercomputation, and the (shaky) historical case for Turing's own interest in such alternative models. Finally, there is Turing the man: gay, criminalised, condemned to receive injections of oestrogen, probably suicidal, and treated as a security risk by the countries whose freedom he helped to ensure.

LRB 1 December 2005 | PDF Download